JPS61180805A - Method of controlling coordination of boiler-steam temperature - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to boiler steam temperature control using a water injection desuperheater, and particularly to cooperative control that suppresses mutual interference between steam flow rate fluctuations due to water injection and unit output control. The present invention relates to an automatic plant control device that enables improved controllability of steam temperature.

[Background of the invention]

The controllability of power plants depends on the controllability of steam temperature. Steam temperature is difficult to control due to large time constants and dead times, accompanied by heat transfer delays and capacity effects in the superheater metal.

FIG. 3 is a typical control system diagram for controlling the steam temperature and turbine output of the drum boiler. The steam generated in the drum 1 is superheated in a primary superheater 2 and a secondary superheater 4, for example,
As disclosed in Japanese Patent Publication No. 54-24681, the water injection control is performed such that deheated water 8 is injected by the regulator 7 and the water injection valve 9 so that the main steam temperature 5 becomes the set value 6 in the water injection desuperheater 3. The unit output control is performed by controlling the output of the turbine 14 by adjusting the control valve 13 with the regulator 12 so that the amount of power generation 10 becomes the required value 11. Figure 4 shows the characteristics of water injection control.

Since the turbine inlet steam flow rate W3 is controlled to an amount commensurate with the unit output, changes in the water injection amount W2 are absorbed by the steam amount W1 from the drum, so the characteristics when the load changes are as shown by the broken line. . In particular, the amount of heat transferred from the flue gas at 2 is the amount of heat held by the metal, so when Wl decreases, the enthalpy 11 of Wl tends to increase. When the enthalpy of the fluid is 11 to i3, the temperature reduction characteristics due to water injection are shown as follows.

W11□+W,i,=Wi.

Since W1+W,=W, Wz/Ws= (111a)/(it lx).

Since 1t-i3>>i knee 12, the variation of 11 is expressed as W, /W, ShinK(xl xa). Based on this characteristic, there is no problem when W, /W is small, but in the case of a large plant, if early water injection control is performed, there is a drawback that the fluctuation in the amount of water injection becomes large.

[Purpose of the invention]

An object of the present invention is to provide a boiler automatic control device that improves controllability of steam temperature by suppressing interference with unit output control in steam temperature control by cooling water injection, thereby improving plant controllability. It's about doing.

[Summary of the invention]

The key point of the present invention is to vary the steam volume at the desuperheater outlet within the allowable range of unit output control only when the amount of water injected changes, thereby suppressing fluctuations in the steam volume at the desuperheater inlet, thereby improving the temperature reduction effect. ,
The purpose is to improve controllability of steam temperature by enabling quick water injection control.

(Embodiment of the Invention) An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In Fig. 1, the amount of water injected is detected by the flow rate detector 15, the amount of change is calculated by the differentiator 16, the phase is adjusted by the signal delayer 17, the unit mask allowable correction amount is created by the signal limiter 18, and the output is This is the part that has been implemented in addition to the amount required by the control device. The effects of this implementation are shown in Figure 2. In particular, since the fluctuations in Wl are suppressed, the fluctuations in W2 are reduced, and as W increases, the amount of heat carried away by the steam increases. Since the temperature reduction effect is improved and interference between water injection control and unit output control is suppressed, water injection control can be improved, which has the effect of improving steam temperature controllability and plant controllability. .

〔Effect of the invention〕

According to the present invention, in addition to the temperature reduction effect due to water injection.

In addition to the temperature reduction effect due to the increased steam flow rate, it is also possible to improve water injection control, which improves steam temperature control, improves plant controllability, and reduces the amount of water injection. , it is also possible to improve plant efficiency.

[Brief explanation of drawings]

Fig. 1 is a schematic system diagram of an embodiment of the present invention, Fig. 2 is a characteristic diagram of water injection, steam amount and steam temperature of an embodiment of the present invention, and Fig. 3
The figure is a conventional system diagram, and FIG. 4 is a conventional characteristic diagram. 15...Flow rate detector, 16...Differentiator, 17...
Signal delay device, 18... signal limiter. Agent: Patent attorney Katsuo Ogawa: Mo17 Mo2Z

Claims (1)

[Claims] 1. In a power generation plant, when the steam temperature is controlled by a water injection cooling device, the output of the unit is controlled by adding a unit output correction based on the water injection amount change due to the water injection control to the turbine control valve operation based on the output control of the unit. A method for cooperatively controlling boiler steam temperature characterized by suppressing interference with water injection temperature reduction control by